1. Field of the Invention
The present invention relates to a work station and method for preparing a bone-tendon-bone graft for anterior cruciate ligament reconstruction.
2. Description of the Related Art
When a ligament or tendon becomes detached from the bone, surgery is usually required to re-secure the ligament or tendon. Often, a substitute ligament or graft is attached to the bone to facilitate regrowth and permanent attachment. The reattachment procedure involves drilling of a graft tunnel between two bones, for example, the tibia and the femur.
To achieve optimal results, it is important that the graft tunnel be drilled at a particular angle and location through the tibia and femur. This can be accomplished by using a variety of tools, such as sighting devices or marking hooks. See U.S. Pat. No. 5,269,786 and U.S. Pat. No. 5,320,626, assigned to the same assignee as the present application, for examples of such devices.
A surgical device for coring the bones can be used to create the graft tunnel and includes means for conveniently removing the cut-out bone from the instrument. The coring reamer of parent application Ser. No. 08/019,356 creates a tibial or femoral tunnel and simultaneously produces a cancellus bone graft which can be used, for example, to fill a patella tendon graft harvesting site at the tibial tubercle and patella of the knee during ACL reconstruction.
The coring reamer of application Ser. No. 08/019,356 includes an elongated collared guide pin which is inserted through the guide pin tunnel in the tibia. A cannulated core saw is inserted over the collared guide pin for drilling the tibia tunnel. A collar is spaced a predetermined distance from one end of the guide pin. As the core saw advances over the collared guide pin in drilling the tunnel, the bone mass generated by the drilling procedure fills the core of the reamer and pushes the collar back into the core.
Upon completion of drilling, the pin, saw, and the contained bone mass are removed from the patient's body. The core of bone mass is then removed from the core saw by tapping the end of the collared guide furthest from the collar. The core of bone mass can then be cut in half and used as bone blocks for subsequent hamstring graft fixation or filling of a harvested graft site.
The bone blocks can be wedged to the wall of a graft tunnel formed through the bone using an interference screw. See U.S. Pat. No. 5,211,647, assigned to the same assignee of the present application, for an example of this device.
A patellar tendon having attached tibial tubercle and patellar bone plugs is often used as an ACL graft. The bone-patellar tendon-bone graft is harvested together in one piece removing one bone block from the patella and one bone block from the tibia, with the tendon extending therebetween. However, since separate bone blocks must be harvested, several incisions must be made in the patient's knee to remove the patellar tendon-bone graft.
Special attention is required when tensioning both the patellar-tendon graft and the bone-hamstring tendon-bone graft. In particular, proper tensioning of the graft prior to fixation decreases elongation of the graft once it is in place. The tension of the graft must be sufficient in order to achieve stability, but not so excessive that it captures the joint. See, e.g., Rubenstein et al., "Graft Selection, Placement, Fixation, and Tensioning for Anterior Cruciate Ligament Reconstruction", Operative Tech in Sports Med., Vol 1, No. 1, p. 13 (1993).
Ordinarily, the graft is inserted through the prepared tunnel and tensioned prior to being secured by moving the knee through a range of motion. One method of determining the proper tension is by using an isometer to measure the tension change at different points. See e.g., Brand et al., "Considerations in the Placement of an Intra-articular Anterior Cruciate Ligament Graft", Operative Tech. in Orthop., Vol. 2, No. 2 (1992). However, tensioning of the graft after the graft is partially in place in the tibial tunnel is cumbersome.